Kelvin K Tran

6400229, Jun 4, 2002

Feb 22, 2001

09/790796

Kelvin T. Tran - Carson CA
Clifford Duong - Fountain Valley CA
Michael N. Farias - San Diego CA
Don C. Devendorf - Carlsbad CA
Lloyd F. Linder - Agoura Hills CA

Raytheon Company - Lexington MA

H03F 122

330311, 330 98

A low noise, low distortion radio frequency amplifier which includes a bootstrap design to minimize intermodulation distortion while simultaneously achieving low noise and wide bandwidth. In the illustrative embodiment, the invention includes a first circuit for receiving an input signal; a second circuit for amplifying the input signal using a transistor Q ; and a third circuit for regulating a rate of change of voltage across the transistor Q such that the rate of voltage change is zero. The third circuit includes a transistor Q connected to the transistor Q in cascode. In the specific illustrative embodiment, the third circuit further includes two diodes D and D used to modulate the voltage at the input of the transistor Q in proportion to the voltage modulation at the input of the transistor Q. In the illustrative embodiment, the second circuit includes a transistor Q connected in cascade to the transistor Q. In the specific illustrative embodiment, the invention further includes a fourth circuit for regulating a rate of change of voltage across the transistor Q such that the rate of voltage change is zero.

7071781, Jul 4, 2006

Dec 18, 2003

10/740172

Seth L. Everton - Torrance CA, US
Lloyd F. Linder - Agoura Hills CA, US
Michael H. Liou - Northridge CA, US
Tom A. Spargo - Hermosa Beach CA, US
Kelvin T. Tran - Torrance CA, US

TelASIC Communications, Inc. - El Segundo CA

H03F 3/45

330261, 330260, 330297

An amplifier. The novel amplifier includes a first circuit for receiving and amplifying an input signal and outputting an output signal, and a second circuit for supplying power to the first circuit, wherein the power supplied varies in accordance with variations in the output signal. The second circuit includes a bootstrapping circuit adapted to regulate the voltages across any transistors in the signal path such that the voltages remain constant. In an illustrative embodiment, the second circuit bootstraps the voltages across a PMOS current source that acts as the load to an input stage, as well as a Darlington pair in an output stage of the amplifier.

7990185, Aug 2, 2011

May 12, 2008

12/119394

Kelvin Tran - Torrance CA, US
Matthias Bussmann - Los Angeles CA, US
Lloyd Linder - Agoura Hills CA, US
Salam Elahmadi - Dallas TX, US
Harry Tan - Palos Verdes CA, US

Menara Networks - Dallas TX

H03M 1/06
H04B 1/10
H03K 5/153

327 96, 327552, 341122

According to one embodiment of the invention, a programmable finite impulse response (FIR) filter is implemented with differential isolation circuits to isolate parasitic capacitance from attenuating an output signal at both first and second differential output terminals of the FIR filter. The FIR includes a track and hold circuit and a summing circuit that provides operational advantages to the FIR filter.

8085079, Dec 27, 2011

Jul 8, 2010

12/832844

Kelvin Tran - Torrance CA, US
Matthias Bussmann - Los Angeles CA, US
Lloyd Linder - Agoura Hills CA, US
Salam Elahmadi - Dallas TX, US
Harry Tan - Palos Verdes CA, US

Menara Networks - Dallas TX

H03K 17/60
H03M 1/66

327361, 327552, 327561, 330 69, 330252, 708670

According to one embodiment of the invention, a summing circuit comprises a first transmitter, a second transmitter, a first current offset circuit and a first transconductance amplifier. The first current offset circuit is coupled to the emitters of the first and second transistors. The first transconductance amplifier is coupled to the first current offset circuit.

58567607, Jan 5, 1999

Nov 7, 1996

8/745070

Khanh Lam - El Monte CA
Lloyd F. Linder - Agoura Hills CA
Carrie C. Lo - Costa Mesa CA
Tim M. Ng - Monterey Park CA
Kelvin T. Tran - Carson CA

Raytheon Company - El Segundo CA

H03F 152

330298

A low-noise, low-distortion clamping scheme includes a bootstrapped voltage clamp and an R. sub. gm current clamp that provide superior overdrive protection when used together in a Class-AB feedback amplifier. The bootstrapped voltage clamp includes a transistor that is connected to a circuit node to be clamped. The transistor's base is bootstrapped to the node to maintain a constant V. sub. be when not clamping, to reduce the adverse effects of the junction capacitance C. sub. je which would normally vary with the node voltage and distort the signal at the node. Two such clamps provide positive and negative voltage limiting. The R. sub. gm current clamp is used in the input stage of a Class-AB feedback amplifier to limit the current through the resistor R. sub. gm that interconnects the current inputs of two transconductance amplifiers whenever the voltage drop across R. sub. gm increases to an unacceptable level.

58595694, Jan 12, 1999

Apr 14, 1997

8/843200

Hieu M. Le - Midway City CA
Lloyd F. Linder - Agoura Hills CA
Erick M. Hirata - Torrance CA
Benjamin Felder - Saugus CA
Roger N. Kosaka - Torrance CA
Donald G. McMullin - Rancho Santa Margarita CA
Kelvin T. Tran - Carson CA

Raytheon Company - El Segundo CA

H02H 720
H03M 112

330298

A current steering circuit diverts bias current from a differential current summing amplifier's front end when the differential input exceeds a safe threshold level, thus preventing the amplifier's output stage from being overdriven. Diverting the front end's bias currents also turns off transistors within the amplifier's front end and thus protects the front end from damage which may otherwise result from excessive input signals.

53152310, May 24, 1994

Nov 16, 1992

7/976760

Lloyd F. Linder - Agora Hills CA
Dwight D. Birdsall - Norwalk CA
Kelvin T. Tran - Carson CA

Hughes Aircraft Company - Los Angeles CA

G05F 326

323315

A bandgap reference voltage source (104) has positive and negative terminals (104a,104b) which are connected through high impedance constant current sources (124c,126c) to positive and negative voltage supplies (+VDD,-VEE) respectively. The effect of variations of the voltage supplies (+VDD, -VEE) on the voltage source (104) is low due to the high impedances of the currents sources (124c,126c), providing a high power supply rejection ratio (PSRR). The reference voltage (VREF) generated by the voltage source (104) is converted into a reference current (IREF) which flows through two equal series resistors (108,110), and also through current mirrors (124,126) which produce positive and negative output currents corresponding thereto. The current sources (124c,126c) for the voltage source (104) are also controlled by the current mirrors (124,126). A servo control amplifier (232) senses the voltage at the junction (234) of the resistors (108,110) and adjusts the voltage at either the positive or negative terminal (104a,104b) of the voltage source (104) to maintain the voltages at the terminals (104a,104b) symmetrical with respect to ground, thereby preventing the voltage source (104) from latching to one of the voltage supplies (+VDD,-VEE) during startup.

54102740, Apr 25, 1995

Mar 17, 1994

8/210269

Dwight D. Birdsall - Norwalk CA
Phillip L. Elliott - Loveland CO
Lloyd F. Linder - Agora CA
Kelvin T. Tran - Carson CA
Donald G. McMullin - Beverly Hills CA

Hughes Aircraft Company - Los Angeles CA

H03F 326
H03F 345

330265

First and second current feedback transconductance amplifiers (102,104) each have a high impedance voltage input, a low impedance current input and a pair of push-pull current outputs. In a single-ended configuration, an input signal is applied to the voltage input of the first transconductance amplifier (102) and the push-pull outputs of the both transconductance amplifiers are connected through a current mirror (136,138) to a node (134) where the current outputs are summed. The node current is integrated by a capacitor (174) to produce a voltage which is amplified by a transimpedance amplifier (190) to produce an output voltage which is fed back to the voltage input of the second transconductance amplifier (104). The current inputs of the transconductance amplifiers (102,104) are interconnected by a resistor (132). The high impedance voltage inputs produce common-mode cancellation of distortion in the transconductance amplifiers (102,104) and low input shot noise.